1
|
Zhu X, Wu K, Anderson SW, Zhang X. Wearable Coaxially-Shielded Metamaterial for Magnetic Resonance Imaging. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2313692. [PMID: 38569592 DOI: 10.1002/adma.202313692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 03/04/2024] [Indexed: 04/05/2024]
Abstract
Recent advancements in metamaterials have yielded the possibility of a wireless solution to improve signal-to-noise ratio (SNR) in magnetic resonance imaging (MRI). Unlike traditional closely packed local coil arrays with rigid designs and numerous components, these lightweight, cost-effective metamaterials eliminate the need for radio frequency cabling, baluns, adapters, and interfaces. However, their clinical adoption is limited by their low sensitivity, bulky physical footprint, and limited, specific use cases. Herein, a wearable metamaterial developed using commercially available coaxial cable, designed for a 3.0 T MRI system is introduced. This metamaterial inherits the coaxially-shielded structure of its constituent cable, confining the electric field within and mitigating coupling to its surroundings. This ensures safer clinical adoption, lower signal loss, and resistance to frequency shifts. Weighing only 50 g, the metamaterial maximizes its sensitivity by conforming to the anatomical region of interest. MRI images acquired using this metamaterial with various pulse sequences achieve an SNR comparable or even surpass that of a state-of-the-art 16-channel knee coil. This work introduces a novel paradigm for constructing metamaterials in the MRI environment, paving the way for the development of next-generation wireless MRI technology.
Collapse
Affiliation(s)
- Xia Zhu
- Department of Mechanical Engineering, Boston University, Boston, MA, 02215, USA
- Photonics Center, Boston University, Boston, MA, 02215, USA
| | - Ke Wu
- Department of Mechanical Engineering, Boston University, Boston, MA, 02215, USA
- Photonics Center, Boston University, Boston, MA, 02215, USA
| | - Stephan W Anderson
- Photonics Center, Boston University, Boston, MA, 02215, USA
- Department of Radiology, Boston University Chobanian & Avedisian School of Medicine, Boston, MA, 02118, USA
| | - Xin Zhang
- Department of Mechanical Engineering, Boston University, Boston, MA, 02215, USA
- Photonics Center, Boston University, Boston, MA, 02215, USA
| |
Collapse
|
2
|
Motovilova E, Ching T, Vincent J, Tan ET, Taracila V, Robb F, Hashimoto M, Sneag DB, Winkler SA. Design and Dynamic In Vivo Validation of a Multi-Channel Stretchable Liquid Metal Coil Array. MATERIALS (BASEL, SWITZERLAND) 2024; 17:3325. [PMID: 38998405 PMCID: PMC11243347 DOI: 10.3390/ma17133325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2024] [Revised: 07/03/2024] [Accepted: 07/03/2024] [Indexed: 07/14/2024]
Abstract
Recent developments in the field of radiofrequency (RF) coils for magnetic resonance imaging (MRI) offer flexible and patient-friendly solutions. Previously, we demonstrated a proof-of-concept single-element stretchable coil design based on liquid metal and a self-tuning smart geometry. In this work, we numerically analyze and experimentally study a multi-channel stretchable coil array and demonstrate its application in dynamic knee imaging. We also compare our flexible coil array to a commonly used commercial rigid coil array. Our numerical analysis shows that the proposed coil array maintains its resonance frequency (<1% variation) and sensitivity (<6%) at various stretching configurations from 0% to 30%. We experimentally demonstrate that the signal-to-noise ratio (SNR) of the acquired MRI images is improved by up to four times with the stretchable coil array due to its conformal and therefore tight-fitting nature. This stretchable array allows for dynamic knee imaging at different flexion angles, infeasible with traditional, rigid coil arrays. These findings are significant as they address the limitations of current rigid coil technology, offering a solution that enhances patient comfort and image quality, particularly in applications requiring dynamic imaging.
Collapse
Affiliation(s)
- Elizaveta Motovilova
- Department of Radiology, Weill Cornell Medicine, New York, NY 10065, USA
- Department of Radiology and Imaging, Hospital for Special Surgery, New York, NY 10021, USA
| | - Terry Ching
- Pillar of Engineering Product Development, Singapore University of Technology and Design, Singapore 487372, Singapore
- Digital Manufacturing and Design (DManD) Centre, Singapore University of Technology and Design, Singapore 487372, Singapore
- Department of Biomedical Engineering, National University of Singapore, Singapore 117583, Singapore
| | | | - Ek Tsoon Tan
- Department of Radiology and Imaging, Hospital for Special Surgery, New York, NY 10021, USA
| | | | | | - Michinao Hashimoto
- Pillar of Engineering Product Development, Singapore University of Technology and Design, Singapore 487372, Singapore
- Digital Manufacturing and Design (DManD) Centre, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Darryl B Sneag
- Department of Radiology and Imaging, Hospital for Special Surgery, New York, NY 10021, USA
| | | |
Collapse
|
3
|
Narongrit FW, Ramesh TV, Rispoli JV. Stretching the Limits of MRI-Stretchable and Modular Coil Array Using Conductive Thread Technology. IEEE ACCESS : PRACTICAL INNOVATIONS, OPEN SOLUTIONS 2024; 12:89613-89620. [PMID: 39026966 PMCID: PMC11257367 DOI: 10.1109/access.2024.3416869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
Objective We propose a modular stretchable coil design using conductive threads and commercially available embroidery machines. The coil design increases customizability of coil arrays for individual patients and each body part. Methods Eight rectangular coils were constructed with custom-fabricated stretchable tinsel copper threads incorporated onto textile. Tune, match, and detune circuits were incorporated on the coil. A hook-and-loop mechanism was used to attach and decouple the modular coils. Phantom and in vivo scans at various anatomical flexion angles were acquired to highlight performance, and a temperature test was performed to verify safety. Results In vivo MRI experiments demonstrate high sensitivity and coverage of each anatomy. As the coils are stretched, the sensitive volume increases at a rate of 10.93 mL/cm2. The SNR reduction of a single coil was greater during compression than when stretched, but this did not affect image quality for the array. The modularity of the array allows for adaptability for any anatomy with simple on-demand adjustment to the number and position of coil elements. Conclusion The images demonstrated high sensitivity and coverage of the stretchable array for various anatomies and flexion angles. Stretching the coils increases the sensitive volume, allowing for a larger region to be effectively imaged. The resonance shift and SNR decrease during stretch and compression support further investigation of methods to reduce frequency shift in stretchable coils. Significance The proposed array design allows for highly stretchable, flexible, modular, and conformal patient-centered coils that allow for increased imaging quality, greater comfort, and rapid production.
Collapse
Affiliation(s)
- Folk W Narongrit
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN 47907, USA
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Thejas Vishnu Ramesh
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Joseph V Rispoli
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN 47907, USA
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA
- Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, VA 22903, USA
| |
Collapse
|
4
|
Wu K, Zhu X, Anderson SW, Zhang X. Wireless, customizable coaxially shielded coils for magnetic resonance imaging. SCIENCE ADVANCES 2024; 10:eadn5195. [PMID: 38865448 PMCID: PMC11168459 DOI: 10.1126/sciadv.adn5195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 05/08/2024] [Indexed: 06/14/2024]
Abstract
Anatomy-specific radio frequency receive coil arrays routinely adopted in magnetic resonance imaging (MRI) for signal acquisition are commonly burdened by their bulky, fixed, and rigid configurations, which may impose patient discomfort, bothersome positioning, and suboptimal sensitivity in certain situations. Herein, leveraging coaxial cables' inherent flexibility and electric field confining property, we present wireless, ultralightweight, coaxially shielded, passive detuning MRI coils achieving a signal-to-noise ratio comparable to or surpassing that of commercially available cutting-edge receive coil arrays with the potential for improved patient comfort, ease of implementation, and substantially reduced costs. The proposed coils demonstrate versatility by functioning both independently in form-fitting configurations, closely adapting to relatively small anatomical sites, and collectively by inductively coupling together as metamaterials, allowing for extension of the field of view of their coverage to encompass larger anatomical regions without compromising coil sensitivity. The wireless, coaxially shielded MRI coils reported herein pave the way toward next-generation MRI coils.
Collapse
Affiliation(s)
- Ke Wu
- Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA
- Photonics Center, Boston University, Boston, MA 02215, USA
| | - Xia Zhu
- Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA
- Photonics Center, Boston University, Boston, MA 02215, USA
| | - Stephan W. Anderson
- Photonics Center, Boston University, Boston, MA 02215, USA
- Boston University Chobanian and Avedisian School of Medicine, Boston, MA 02118, USA
| | - Xin Zhang
- Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA
- Photonics Center, Boston University, Boston, MA 02215, USA
| |
Collapse
|
5
|
Vazquez R, Motovilova E, Winkler SA. Stretchable Sensor Materials Applicable to Radiofrequency Coil Design in Magnetic Resonance Imaging: A Review. SENSORS (BASEL, SWITZERLAND) 2024; 24:3390. [PMID: 38894182 PMCID: PMC11174967 DOI: 10.3390/s24113390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 05/19/2024] [Accepted: 05/21/2024] [Indexed: 06/21/2024]
Abstract
Wearable sensors are rapidly gaining influence in the diagnostics, monitoring, and treatment of disease, thereby improving patient outcomes. In this review, we aim to explore how these advances can be applied to magnetic resonance imaging (MRI). We begin by (i) introducing limitations in current flexible/stretchable RF coils and then move to the broader field of flexible sensor technology to identify translatable technologies. To this goal, we discuss (ii) emerging materials currently used for sensor substrates, (iii) stretchable conductive materials, (iv) pairing and matching of conductors with substrates, and (v) implementation of lumped elements such as capacitors. Applicable (vi) fabrication methods are presented, and the review concludes with a brief commentary on (vii) the implementation of the discussed sensor technologies in MRI coil applications. The main takeaway of our research is that a large body of work has led to exciting new sensor innovations allowing for stretchable wearables, but further exploration of materials and manufacturing techniques remains necessary, especially when applied to MRI diagnostics.
Collapse
Affiliation(s)
- Rigoberto Vazquez
- Department of Biomedical Engineering, Cornell University, Ithaca, NY 10065, USA
- Department of Radiology, Weill Cornell Medicine, New York, NY 10065, USA
| | | | - Simone Angela Winkler
- Department of Biomedical Engineering, Cornell University, Ithaca, NY 10065, USA
- Department of Radiology, Weill Cornell Medicine, New York, NY 10065, USA
| |
Collapse
|
6
|
Nohava L, Czerny R, Tik M, Wurzer D, Laistler E, Frass-Kriegl R. Citizen science approach to assessing patient perception of MRI with flexible radiofrequency coils. Sci Rep 2024; 14:2811. [PMID: 38307928 PMCID: PMC10837436 DOI: 10.1038/s41598-024-53364-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 01/30/2024] [Indexed: 02/04/2024] Open
Abstract
Magnetic Resonance Imaging (MRI) is a major medical imaging modality, which is non-invasive and provides unique soft tissue contrast without ionizing radiation. The successful completion of MRI exams critically depends on patient compliance, and, thus patient comfort. The design, appearance and usability of local MRI radiofrequency (RF) coils potentially influences the patients' perception of the exam. However, systematic investigations and empirical evidence for these aspects are missing. A questionnaire specifically evaluating the impact of RF coils on patient comfort in MRI would be a valuable addition to clinical studies comparing the performance of novel flexible RF coils with standard rigid coils. This paper describes the development of such a questionnaire in the scope of a citizen science (CS) initiative conducted with a group of students at the upper secondary school level. In this work, the CS initiative is presented in the format of a case report and its impact on scientific projects and the students' education is outlined. The resulting questionnaire is made available in German and English so as to be directly applicable by researchers working on the clinical evaluation of novel RF coils or the comfort evaluation of specific hardware setups in general.
Collapse
Affiliation(s)
- Lena Nohava
- High Field MR Center, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Raphaela Czerny
- High Field MR Center, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Martin Tik
- High Field MR Center, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Dagmar Wurzer
- Bundes(real)gymnasium BG/BRG Keimgasse, Mödling, Austria
| | - Elmar Laistler
- High Field MR Center, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Roberta Frass-Kriegl
- High Field MR Center, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
| |
Collapse
|
7
|
Motovilova E, Ching T, Vincent J, Shin J, Tan ET, Taracila V, Robb F, Hashimoto M, Sneag DB, Winkler SA. Dual-Channel Stretchable, Self-Tuning, Liquid Metal Coils and Their Fabrication Techniques. SENSORS (BASEL, SWITZERLAND) 2023; 23:7588. [PMID: 37688046 PMCID: PMC10490642 DOI: 10.3390/s23177588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 08/28/2023] [Accepted: 08/29/2023] [Indexed: 09/10/2023]
Abstract
Flexible and stretchable radiofrequency coils for magnetic resonance imaging represent an emerging and rapidly growing field. The main advantage of such coil designs is their conformal nature, enabling a closer anatomical fit, patient comfort, and freedom of movement. Previously, we demonstrated a proof-of-concept single element stretchable coil design with a self-tuning smart geometry. In this work, we evaluate the feasibility of scaling this coil concept to a multi-element coil array and the associated engineering and manufacturing challenges. To this goal, we study a dual-channel coil array using full-wave simulations, bench testing, in vitro, and in vivo imaging in a 3 T scanner. We use three fabrication techniques to manufacture dual-channel receive coil arrays: (1) single-layer casting, (2) double-layer casting, and (3) direct-ink-writing. All fabricated arrays perform equally well on the bench and produce similar sensitivity maps. The direct-ink-writing method is found to be the most advantageous fabrication technique for fabrication speed, accuracy, repeatability, and total coil array thickness (0.6 mm). Bench tests show excellent frequency stability of 128 ± 0.6 MHz (0% to 30% stretch). Compared to a commercial knee coil array, the stretchable coil array is more conformal to anatomy and provides 50% improved signal-to-noise ratio in the region of interest.
Collapse
Affiliation(s)
- Elizaveta Motovilova
- Department of Radiology, Weill Cornell Medicine, New York, NY 10065, USA
- Department of Radiology and Imaging, Hospital for Special Surgery, New York, NY 10021, USA
| | - Terry Ching
- Pillar of Engineering Product Development, Singapore University of Technology and Design, Singapore 487372, Singapore
- Digital Manufacturing and Design (DManD) Centre, Singapore University of Technology and Design, Singapore 487372, Singapore
- Department of Biomedical Engineering, National University of Singapore, Singapore 117583, Singapore
| | | | - James Shin
- Department of Radiology, Weill Cornell Medicine, New York, NY 10065, USA
| | - Ek Tsoon Tan
- Department of Radiology and Imaging, Hospital for Special Surgery, New York, NY 10021, USA
| | | | | | - Michinao Hashimoto
- Pillar of Engineering Product Development, Singapore University of Technology and Design, Singapore 487372, Singapore
- Digital Manufacturing and Design (DManD) Centre, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Darryl B. Sneag
- Department of Radiology and Imaging, Hospital for Special Surgery, New York, NY 10021, USA
| | | |
Collapse
|
8
|
Vishnu Ramesh T, Narongrit FW, Susnjar A, Rispoli JV. Stretchable receive coil for 7T small animal MRI. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 353:107510. [PMID: 37343393 DOI: 10.1016/j.jmr.2023.107510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 05/15/2023] [Accepted: 06/10/2023] [Indexed: 06/23/2023]
Abstract
Receive coils used in small animal MRI are rigid, inflexible surface loops that do not conform to the anatomy being imaged. The recent trend toward design of stretchable coils that are tailored to fit any anatomical curvature has been focused on human imaging. This work demonstrates the application of stretchable coils for small animal imaging at 7T. A stretchable coil measuring 3.5 × 3.5 cm was developed for acquisition of rat brain and spine images. The SNR maps of the stretchable coil were compared with those of a traditional flexible PCB coil and a commercial surface coil. Stretch and conformance testing of the coil was performed. Ex vivo images of rat brain and spine from the stretchable a coil was acquired using T1 FLASH and T2 Turbo RARE sequences. The axial phantom SNR maps showed that the stretchable coil provided 48.5% and 42.8% higher SNR than the commercial coil for T1-w and T2-w images within the defined ROI. A 33% increase in average penetration depth was observed within the ROI using the stretchable coil when compared to the commercial coil. The ex-vivo rat brain and spine images showed distinguishable anatomical details. Stretching the coil reduced the resonant frequency with reduction in SNR, while the conformance to varying sample volumes increased the resonant frequency with decreased SNR. This study also features an open-source plug-and-play system with preamplifiers that can be used to interface surface coils with the 7T Bruker scanner.
Collapse
Affiliation(s)
- Thejas Vishnu Ramesh
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Folk W Narongrit
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA; Elmore Family School of Electrical and Computer Engineering, West Lafayette, IN 47907, USA
| | - Antonia Susnjar
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Joseph V Rispoli
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA; Elmore Family School of Electrical and Computer Engineering, West Lafayette, IN 47907, USA; Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, VA 22903, USA.
| |
Collapse
|
9
|
Karasan E, Hammerschmidt A, Arias AC, Taracila V, Robb F, Lustig M. Caterpillar traps: A highly flexible, distributed system of toroidal cable traps. Magn Reson Med 2023; 89:2471-2484. [PMID: 36695296 PMCID: PMC10278796 DOI: 10.1002/mrm.29584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 12/05/2022] [Accepted: 12/29/2022] [Indexed: 01/26/2023]
Abstract
PURPOSE Coil arrays are connected to the main MRI system with long, shielded coaxial cables. RF coupling of these cables to the main transmit coil can cause high shield currents, which pose risks of heating and RF burns. High-blocking resonant RF traps are placed at distinct positions along cables to mitigate these currents. Traditional traps are designed to be stiff to avoid changes in their resonant frequency, hindering the overall system flexibility. Instead of using a few high-blocking traps, we propose the use of caterpillar traps-a distributed system of small, elastic traps that cover the full length of cables. METHODS We leverage an array of resonant toroids as traps, forming a caterpillar-like structure whereby bending only impacts individual traps minimally. Benchtop measurements are used to determine the blocking of caterpillar traps and show their robustness to bending. We also compare an anterior array system cable covered with caterpillar traps to a commercial cable with B1 + and heating measurements. RESULTS Benchtop experiments with caterpillar traps demonstrate high robustness to bending. B1 + mapping experiments of an anterior array cable show improved blocking and flexibility compared to a commercial cable. CONCLUSION Caterpillar traps provide sufficient attenuation to shield currents while allowing cable flexibility. Our distributed design can provide high blocking efficiency at different positions and orientations, even in cases where commercial cable traps cannot.
Collapse
Affiliation(s)
- Ekin Karasan
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA, USA
| | | | - Ana Claudia Arias
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA, USA
| | | | | | - Michael Lustig
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA, USA
| |
Collapse
|
10
|
Wang B, Siddiq SS, Walczyk J, Bruno M, Khodarahmi I, Brinkmann IM, Rehner R, Lakshmanan K, Fritz J, Brown R. A flexible MRI coil based on a cable conductor and applied to knee imaging. Sci Rep 2022; 12:15010. [PMID: 36056131 PMCID: PMC9440226 DOI: 10.1038/s41598-022-19282-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 08/26/2022] [Indexed: 11/08/2022] Open
Abstract
Flexible radiofrequency coils for magnetic resonance imaging (MRI) have garnered attention in research and industrial communities because they provide improved accessibility and performance and can accommodate a range of anatomic postures. Most recent flexible coil developments involve customized conductors or substrate materials and/or target applications at 3 T or above. In contrast, we set out to design a flexible coil based on an off-the-shelf conductor that is suitable for operation at 0.55 T (23.55 MHz). Signal-to-noise ratio (SNR) degradation can occur in such an environment because the resistance of the coil conductor can be significant with respect to the sample. We found that resonating a commercially available RG-223 coaxial cable shield with a lumped capacitor while the inner conductor remained electrically floating gave rise to a highly effective "cable coil." A 10-cm diameter cable coil was flexible enough to wrap around the knee, an application that can benefit from flexible coils, and had similar conductor loss and SNR as a standard-of-reference rigid copper coil. A two-channel cable coil array also provided good SNR robustness against geometric variability, outperforming a two-channel coaxial coil array by 26 and 16% when the elements were overlapped by 20-40% or gapped by 30-50%, respectively. A 6-channel cable coil array was constructed for 0.55 T knee imaging. Incidental cartilage and bone pathologies were clearly delineated in T1- and T2-weighted turbo spin echo images acquired in 3-4 min with the proposed coil, suggesting that clinical quality knee imaging is feasible in an acceptable examination timeframe. Correcting for T1, the SNR measured with the cable coil was approximately threefold lower than that measured with a 1.5 T state-of-the-art 18-channel coil, which is expected given the threefold difference in main magnetic field strength. This result suggests that the 0.55 T cable coil conductor loss does not deleteriously impact SNR, which might be anticipated at low field.
Collapse
Affiliation(s)
- Bili Wang
- Department of Radiology, Center for Advanced Imaging Innovation and Research (CAI2R), New York University Grossman School of Medicine, 660 First Ave, New York, NY, USA
| | - Syed S Siddiq
- Department of Radiology, Center for Advanced Imaging Innovation and Research (CAI2R), New York University Grossman School of Medicine, 660 First Ave, New York, NY, USA
- Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Jerzy Walczyk
- Department of Radiology, Center for Advanced Imaging Innovation and Research (CAI2R), New York University Grossman School of Medicine, 660 First Ave, New York, NY, USA
| | - Mary Bruno
- Department of Radiology, Center for Advanced Imaging Innovation and Research (CAI2R), New York University Grossman School of Medicine, 660 First Ave, New York, NY, USA
| | - Iman Khodarahmi
- Department of Radiology, Center for Advanced Imaging Innovation and Research (CAI2R), New York University Grossman School of Medicine, 660 First Ave, New York, NY, USA
- Division of Musculoskeletal Radiology, Department of Radiology, New York University Grossman School of Medicine, New York, NY, USA
| | | | | | - Karthik Lakshmanan
- Department of Radiology, Center for Advanced Imaging Innovation and Research (CAI2R), New York University Grossman School of Medicine, 660 First Ave, New York, NY, USA
| | - Jan Fritz
- Department of Radiology, Center for Advanced Imaging Innovation and Research (CAI2R), New York University Grossman School of Medicine, 660 First Ave, New York, NY, USA
- Division of Musculoskeletal Radiology, Department of Radiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Ryan Brown
- Department of Radiology, Center for Advanced Imaging Innovation and Research (CAI2R), New York University Grossman School of Medicine, 660 First Ave, New York, NY, USA.
| |
Collapse
|
11
|
Zhang B, Wang B, Ho J, Hodono S, Burke C, Lattanzi R, Vester M, Rehner R, Sodickson D, Brown R, Cloos M. Twenty-four-channel high-impedance glove array for hand and wrist MRI at 3T. Magn Reson Med 2022; 87:2566-2575. [PMID: 34971464 PMCID: PMC8847333 DOI: 10.1002/mrm.29147] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 12/12/2021] [Accepted: 12/15/2021] [Indexed: 12/29/2022]
Abstract
PURPOSE To present a novel 3T 24-channel glove array that enables hand and wrist imaging in varying postures. METHODS The glove array consists of an inner glove holding the electronics and an outer glove protecting the components. The inner glove consists of four main structures: palm, fingers, wrist, and a flap that rolls over on top. Each structure was constructed out of three layers: a layer of electrostatic discharge flame-resistant fabric, a layer of scuba neoprene, and a layer of mesh fabric. Lightweight and flexible high impedance coil (HIC) elements were inserted into dedicated tubes sewn into the fabric. Coil elements were deliberately shortened to minimize the matching interface. Siemens Tim 4G technology was used to connect all 24 HIC elements to the scanner with only one plug. RESULTS The 24-channel glove array allows large motion of both wrist and hand while maintaining the SNR needed for high-resolution imaging. CONCLUSION In this work, a purpose-built 3T glove array that embeds 24 HIC elements is demonstrated for both hand and wrist imaging. The 24-channel glove array allows a great range of motion of both the wrist and hand while maintaining a high SNR and providing good theoretical acceleration performance, thus enabling hand and wrist imaging at different postures to extract kinematic information.
Collapse
Affiliation(s)
- Bei Zhang
- Center for Advanced Imaging Innovation and Research (CAIR) and Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York, NY, USA
- Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX, USA
| | - Bili Wang
- Center for Advanced Imaging Innovation and Research (CAIR) and Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Justin Ho
- Center for Advanced Imaging Innovation and Research (CAIR) and Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Shota Hodono
- Centre for Advanced Imaging, Queensland University, Brisbane, Australia
| | | | - Riccardo Lattanzi
- Center for Advanced Imaging Innovation and Research (CAIR) and Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York, NY, USA
- Vilcek Institute of Graduate Biomedical Sciences, New York University Grossman School of Medicine, New York, NY, USA
| | | | | | - Daniel Sodickson
- Center for Advanced Imaging Innovation and Research (CAIR) and Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Ryan Brown
- Center for Advanced Imaging Innovation and Research (CAIR) and Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Martijn Cloos
- Center for Advanced Imaging Innovation and Research (CAIR) and Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York, NY, USA
- Centre for Advanced Imaging, Queensland University, Brisbane, Australia
| |
Collapse
|
12
|
Darnell D, Truong TK, Song AW. Recent Advances in Radio-Frequency Coil Technologies: Flexible, Wireless, and Integrated Coil Arrays. J Magn Reson Imaging 2022; 55:1026-1042. [PMID: 34324753 PMCID: PMC10494287 DOI: 10.1002/jmri.27865] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 07/19/2021] [Accepted: 07/19/2021] [Indexed: 12/25/2022] Open
Abstract
Radio-frequency (RF) coils are to magnetic resonance imaging (MRI) scanners what eyes are to the human body. Because of their critical importance, there have been constant innovations driving the rapid development of RF coil technologies. Over the past four decades, the breadth and depth of the RF coil technology evolution have far exceeded the space allowed for this review article. However, these past developments have laid the very foundation on which some of the recent technical breakthroughs are built upon. Here, we narrow our focus on some of the most recent RF coil advances, specifically, on flexible, wireless, and integrated coil arrays. To provide a detailed review, we discuss the theoretical underpinnings, experimental implementations, promising results, as well as future outlooks covering these exciting topics. These recent innovations have greatly improved patient comfort and ease of scan, while also increasing the signal-to-noise ratio, image resolution, temporal throughput, and diagnostic and treatment accuracy. Together with advances in other MRI subfields, they will undoubtedly continue to drive the field forward and lead us to an ever more exciting future. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 1.
Collapse
Affiliation(s)
- Dean Darnell
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina, USA
| | - Trong-Kha Truong
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina, USA
| | - Allen W. Song
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina, USA
| |
Collapse
|
13
|
Saniour I, Robb FJL, Taracila V, Mishra V, Vincent J, Voss HU, Kaplitt MG, Chazen JL, Winkler SA. Characterization of a Low-Profile, Flexible, and Acoustically Transparent Receive-Only MRI Coil Array for High Sensitivity MR-Guided Focused Ultrasound. IEEE ACCESS : PRACTICAL INNOVATIONS, OPEN SOLUTIONS 2022; 10:25062-25072. [PMID: 35600672 PMCID: PMC9119199 DOI: 10.1109/access.2022.3154824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Magnetic resonance guided focused ultrasound (MRgFUS) is a non-invasive therapeutic modality for neurodegenerative diseases that employs real-time imaging and thermometry monitoring of targeted regions. MRI is used in guidance of ultrasound treatment; however, the MR image quality in current clinical applications is poor when using the vendor built-in body coil. We present an 8-channel, ultra-thin, flexible, and acoustically transparent receive-only head coil design (FUS-Flex) to improve the signal-to-noise ratio (SNR) and thus the quality of MR images during MRgFUS procedures. Acoustic simulations/experiments exhibit transparency of the FUS-Flex coil as high as 97% at 650 kHz. Electromagnetic simulations show a SNR increase of 13× over the body coil. In vivo results show an increase of the SNR over the body coil by a factor of 7.3 with 2× acceleration (equivalent to 11× without acceleration) in the brain of a healthy volunteer, which agrees well with simulation. These preliminary results show that the use of a FUS-Flex coil in MRgFUS surgery can increase MR image quality, which could yield improved focal precision, real-time intraprocedural anatomical imaging, and real-time 3D thermometry mapping.
Collapse
Affiliation(s)
- Isabelle Saniour
- Department of Radiology, Weill Cornell Medicine, NewYork-Presbyterian Hospital, New York, NY 10065, USA
| | | | | | - Vishwas Mishra
- Department of Radiology, Weill Cornell Medicine, NewYork-Presbyterian Hospital, New York, NY 10065, USA
| | - Jana Vincent
- MR Engineering, GE Healthcare Coils, Aurora, OH 44202, USA
| | - Henning U Voss
- Department of Radiology, Weill Cornell Medicine, NewYork-Presbyterian Hospital, New York, NY 10065, USA
| | - Michael G Kaplitt
- Department of Neurological Surgery, Weill Cornell Medicine, NewYork-Presbyterian Hospital, New York, NY 10065, USA
| | - J Levi Chazen
- Department of Radiology, Weill Cornell Medicine, NewYork-Presbyterian Hospital, New York, NY 10065, USA
| | - Simone Angela Winkler
- Department of Radiology, Weill Cornell Medicine, NewYork-Presbyterian Hospital, New York, NY 10065, USA
| |
Collapse
|
14
|
Application of Highly Flexible Adaptive Image Receive Coil for Lung MR Imaging Using Zero TE Sequence: Comparison with Conventional Anterior Array Coil. Diagnostics (Basel) 2022; 12:diagnostics12010148. [PMID: 35054316 PMCID: PMC8774338 DOI: 10.3390/diagnostics12010148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 01/06/2022] [Accepted: 01/06/2022] [Indexed: 02/06/2023] Open
Abstract
(1) Background: Highly flexible adaptive image receive (AIR) coil has become available for clinical use. The present study aimed to evaluate the performance of AIR anterior array coil in lung MR imaging using a zero echo time (ZTE) sequence compared with conventional anterior array (CAA) coil. (2) Methods: Sixty-six patients who underwent lung MR imaging using both AIR coil (ZTE-AIR) and CAA coil (ZTE-CAA) were enrolled. Image quality of ZTE-AIR and ZTE-CAA was quantified by calculating blur metric value, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) of lung parenchyma. Image quality was qualitatively assessed by two independent radiologists. Lesion detection capabilities for lung nodules and emphysema and/or lung cysts were evaluated. Patients' comfort levels during examinations were assessed. (3) Results: SNR and CNR of lung parenchyma were higher (both p < 0.001) in ZTE-AIR than in ZTE-CAA. Image sharpness was superior in ZTE-AIR (p < 0.001). Subjective image quality assessed by two independent readers was superior (all p < 0.05) in ZTE-AIR. AIR coil was preferred by 64 of 66 patients. ZTE-AIR showed higher (all p < 0.05) sensitivity for sub-centimeter nodules than ZTE-CAA by both readers. ZTE-AIR showed higher (all p < 0.05) sensitivity and accuracy for detecting emphysema and/or cysts than ZTE-CAA by both readers. (4) Conclusions: The use of highly flexible AIR coil in ZTE lung MR imaging can improve image quality and patient comfort. Application of AIR coil in parenchymal imaging has potential for improving delineation of low-density parenchymal lesions and tiny nodules.
Collapse
|
15
|
Huang P, Xu L, Xie Y. Biomedical Applications of Electromagnetic Detection: A Brief Review. BIOSENSORS 2021; 11:225. [PMID: 34356696 PMCID: PMC8301974 DOI: 10.3390/bios11070225] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 06/29/2021] [Accepted: 07/03/2021] [Indexed: 01/01/2023]
Abstract
This paper presents a review on the biomedical applications of electromagnetic detection in recent years. First of all, the thermal, non-thermal, and cumulative thermal effects of electromagnetic field on organism and their biological mechanisms are introduced. According to the electromagnetic biological theory, the main parameters affecting electromagnetic biological effects are frequency and intensity. This review subsequently makes a brief review about the related biomedical application of electromagnetic detection and biosensors using frequency as a clue, such as health monitoring, food preservation, and disease treatment. In addition, electromagnetic detection in combination with machine learning (ML) technology has been used in clinical diagnosis because of its powerful feature extraction capabilities. Therefore, the relevant research involving the application of ML technology to electromagnetic medical images are summarized. Finally, the future development to electromagnetic detection for biomedical applications are presented.
Collapse
Affiliation(s)
- Pu Huang
- School of Instrumentation and Optoelectronic Engineering, Beihang University, Beijing 100191, China;
| | - Lijun Xu
- Beijing Advanced Innovation Centre for Big Data-Based Precision Medicine, Beihang University, Beijing 100191, China;
| | - Yuedong Xie
- School of Instrumentation and Optoelectronic Engineering, Beihang University, Beijing 100191, China;
- Beijing Advanced Innovation Centre for Big Data-Based Precision Medicine, Beihang University, Beijing 100191, China;
| |
Collapse
|
16
|
Nohava L, Czerny R, Roat S, Obermann M, Kuehne A, Frass-Kriegl R, Felblinger J, Ginefri JC, Laistler E. Flexible Multi-Turn Multi-Gap Coaxial RF Coils: Design Concept and Implementation for Magnetic Resonance Imaging at 3 and 7 Tesla. IEEE TRANSACTIONS ON MEDICAL IMAGING 2021; 40:1267-1278. [PMID: 33439836 DOI: 10.1109/tmi.2021.3051390] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Magnetic resonance has become a backbone of medical imaging but suffers from inherently low sensitivity. This can be alleviated by improved radio frequency (RF) coils. Multi-turn multi-gap coaxial coils (MTMG-CCs) introduced in this work are flexible, form-fitting RF coils extending the concept of the single-turn single-gap CC by introducing multiple cable turns and/or gaps. It is demonstrated that this enables free choice of the coil diameter, and thus, optimizing it for the application to a certain anatomical site, while operating at the self-resonance frequency. An equivalent circuit for MTMG-CCs is modeled to predict their resonance frequency. Possible configurations regarding size, number of turns and gaps, and cable types for different B 0 field strengths are calculated. Standard copper wire loop coils (SCs) and flexible CCs made from commercial coaxial cable were fabricated as receive-only coils for 3 T and transmit/receive coils at 7 T with diameters between 4 and 15 cm. Electromagnetic simulations are used to investigate the currents on MTMG-CCs, and demonstrate comparable specific absorption rate of 7 T CCs and SCs. Signal-to-noise ratio (SNR), transmit efficiency, and active detuning performance of CCs were compared in bench tests and MR experiments. For the form-fitted receive-only CCs at 3 T no significant SNR degradation was found as compared to flat SCs on a balloon phantom. Form-fitted transmit/receive CCs at 7 T showed higher transmit efficiency and SNR. MTMG-CCs can be sized to optimize sensitivity, are flexible and lightweight, and could therefore enable the fabrication of wearable coils with improved patient comfort.
Collapse
|
17
|
Custom, spray coated receive coils for magnetic resonance imaging. Sci Rep 2021; 11:2635. [PMID: 33514816 PMCID: PMC7846777 DOI: 10.1038/s41598-021-81833-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 12/17/2020] [Indexed: 11/08/2022] Open
Abstract
We have developed a process for fabricating patient specific Magnetic Resonance Imaging (MRI) Radio-frequency (RF) receive coil arrays using additive manufacturing. Our process involves spray deposition of silver nanoparticle inks and dielectric materials onto 3D printed substrates to form high-quality resonant circuits. In this paper, we describe the material selection and characterization, process optimization, and design and testing of a prototype 4-channel neck array for carotid imaging. We show that sprayed polystyrene can form a low loss dielectric layer in a parallel plate capacitor. We also demonstrate that by using sprayed silver nanoparticle ink as conductive traces, our devices are still dominated by sample noise, rather than material losses. These results are critical for maintaining high Signal-to-Noise-Ratio (SNR) in clinical settings. Finally, our prototype patient specific coil array exhibits higher SNR (5 × in the periphery, 1.4 × in the center) than a commercially available array designed to fit the majority of subjects when tested on our custom neck phantom. 3D printed substrates ensure an optimum fit to complex body parts, improve diagnostic image quality, and enable reproducible placement on subjects.
Collapse
|
18
|
Port A, Luechinger R, Brunner DO, Pruessmann KP. Elastomer coils for wearable MR detection. Magn Reson Med 2021; 85:2882-2891. [PMID: 33433044 DOI: 10.1002/mrm.28662] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 11/20/2020] [Accepted: 12/07/2020] [Indexed: 01/06/2023]
Abstract
PURPOSE To explore the use of conductive elastomer for MR signal detection and the utility of this approach for wearable detector arrays. METHODS An elastomer filled with silver microparticles was used to form stretchable radiofrequency coils for MR detection. Their electrical performance in terms of the Qunloaded and Q ratio was assessed in the relaxed state and under repeated strain up to 40%. In a phantom imaging study, the signal-to-noise ratio yield of conductive elastomer coils was compared with that of a reference copper coil. Four elastomer coils were integrated with a stretchable textile substrate to form a wearable array for knee imaging. The array was employed for multiple-angle and kinematic knee imaging in vivo. RESULTS The elastomer coils proved highly stretchable and mechanically robust. Upon repeated stretching by 20%, a medium-sized coil element settled at Qunloaded of 42 in the relaxed state and 32 at full strain, reflecting sample-noise dominance. The signal-to-noise ratio of elastomer coils was found to be 8% to 16% lower than that achieved with a conventional copper coil. Multiple-angle and kinematic knee imaging with the wearable array yielded high-quality results indicating robustness of detection performance against stretching and warping of the array. CONCLUSION Conductive elastomer is a viable material for MR detection. Coils made from this material reconcile high stretchability and adequate electrical performance with ease of manufacturing. Conductive elastomer also offers inherent restoring forces and is readily washable and sanitizable, making it an excellent basis of wearable detector front ends.
Collapse
Affiliation(s)
- Andreas Port
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Roger Luechinger
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - David O Brunner
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Klaas P Pruessmann
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| |
Collapse
|
19
|
Barta R, Volotovskyy V, Wachowicz K, Fallone BG, De Zanche N. How thin can you go? Performance of thin copper and aluminum RF coil conductors. Magn Reson Med 2020; 85:2327-2333. [PMID: 33058317 DOI: 10.1002/mrm.28540] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 09/10/2020] [Accepted: 09/11/2020] [Indexed: 11/09/2022]
Abstract
PURPOSE To evaluate the impact of emerging conductor technology on RF coils. Performance and resulting image quality of thin or alternate conductors (eg, aluminum instead of copper) and thicknesses (9-600 μm) are compared in terms of SNR. METHODS Eight prototype RF coils (15 cm × 15 cm square loops) were constructed and bench-tested to measure quality factor. The coils used 6-mm-wide conducting strips of either copper or aluminum of a few different thicknesses (copper: 17, 32, 35, 127, 600 μm; aluminum: 9, 13, 20, 127 μm) on acetate projector sheets for backing. Corresponding image SNR was measured at 0.48 tesla (20.56 MHz). RESULTS The coils spanned a range of unloaded quality factors from 89 to 390 and a fivefold range of losses. The image SNRs were consistent with the coils' bench-measured efficiencies (0.33-0.73). Thin aluminum conductors (9 μm) led to the highest reduction in SNR (65% that of 127 μm copper). Thin copper (<32 μm) conductors lead to a much smaller decrease in SNR (approximately 10%) compared to 127 μm copper. No performance difference was observed between 127 μm thick copper and aluminum. The much thicker 600 μm copper bars only yield a 5% improvement in SNR. CONCLUSION Even at 0.48 tesla, copper RF coil conductors much thinner than those in conventional construction can be used while maintaining SNR greater than 50% that of thick copper. These emerging coil conductor technologies enable RF coil functionality that cannot be achieved otherwise.
Collapse
Affiliation(s)
- Radim Barta
- Department of Oncology, Division of Medical Physics, University of Alberta, Edmonton, Alberta, Canada
| | | | - Keith Wachowicz
- Department of Oncology, Division of Medical Physics, University of Alberta, Edmonton, Alberta, Canada.,Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
| | - B Gino Fallone
- Department of Oncology, Division of Medical Physics, University of Alberta, Edmonton, Alberta, Canada.,Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada.,Department of Physics, University of Alberta, Edmonton, Alberta, Canada
| | - Nicola De Zanche
- Department of Oncology, Division of Medical Physics, University of Alberta, Edmonton, Alberta, Canada.,Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
| |
Collapse
|
20
|
Collick BD, Behzadnezhad B, Hurley SA, Mathew NK, Behdad N, Lindsay SA, Robb F, Stormont RS, McMillan AB. Rapid development of application-specific flexible MRI receive coils. Phys Med Biol 2020; 65:19NT01. [PMID: 32975219 PMCID: PMC8064628 DOI: 10.1088/1361-6560/abaffb] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Over the last 30 years, there have been dramatic changes in phased array coil technology leading to increasing channel density and parallel imaging functionality. Current receiver array coils are rigid and often mismatched to patient's size. Recently there has been a move towards flexible coil technology, which is more conformal to the human anatomy. Despite the advances of so-called flexible surface coil arrays, these coils are still relatively rigid and limited in terms of design conformability, compromising signal-to-noise ratio (SNR) for flexibility, and are not designed for optimum parallel imaging performance. The purpose of this study is to report on the development and characterization of a 15-channel flexible foot and ankle coil, rapidly designed and constructed using highly decoupled radio-frequency (RF) coil elements. Coil performance was evaluated by performing SNR and g-factor measurements. In vivo testing was performed in a healthy volunteer using both the 15-channel coil and a commercially available 8-channel foot coil. The highly decoupled elements used in this design allow for extremely rapid development and prototyping of application-specific coils for different patient sizes (adult vs child) with minimal additional design consideration in terms of coil overlap and geometry. Image quality was comparable to a commercially available RF coil.
Collapse
Affiliation(s)
- B D Collick
- Department of Radiology, University of Wisconsin, Madison, WI 53705, United States of America. Author B D Collick and author B Behzadnezhad contributed equally to this work
| | | | | | | | | | | | | | | | | |
Collapse
|
21
|
Brunnquell CL, Hoff MN, Balu N, Nguyen XV, Oztek MA, Haynor DR. Making Magnets More Attractive: Physics and Engineering Contributions to Patient Comfort in MRI. Top Magn Reson Imaging 2020; 29:167-174. [PMID: 32541257 DOI: 10.1097/rmr.0000000000000246] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Patient comfort is an important factor of a successful magnetic resonance (MR) examination, and improvements in the patient's MR scanning experience can contribute to improved image quality, diagnostic accuracy, and efficiency in the radiology department, and therefore reduced cost. Magnet designs that are more open and accessible, reduced auditory noise of MR examinations, light and flexible radiofrequency (RF) coils, and faster motion-insensitive imaging techniques can all significantly improve the patient experience in MR imaging. In this work, we review the design, development, and implementation of these physics and engineering approaches to improve patient comfort.
Collapse
Affiliation(s)
- Christina L Brunnquell
- Department of Radiology, University of Washington, Seattle, WA Department of Radiology, The Ohio State University Wexler Medical Center, Columbus, OH
| | | | | | | | | | | |
Collapse
|
22
|
Börnert P, Norris DG. A half-century of innovation in technology-preparing MRI for the 21st century. Br J Radiol 2020; 93:20200113. [PMID: 32496816 DOI: 10.1259/bjr.20200113] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
MRI developed during the last half-century from a very basic concept to an indispensable non-ionising medical imaging technique that has found broad application in diagnostics, therapy control and far beyond. Due to its excellent soft-tissue contrast and the huge variety of accessible tissue- and physiological-parameters, MRI is often preferred to other existing modalities. In the course of its development, MRI underwent many substantial transformations. From the beginning, starting as a proof of concept, much effort was expended to develop the appropriate basic scanning technology and methodology, and to establish the many clinical contrasts (e.g., T1, T2, flow, diffusion, water/fat, etc.) that MRI is famous for today. Beyond that, additional prominent innovations to the field have been parallel imaging and compressed sensing, leading to significant scanning time reductions, and the move towards higher static magnetic field strengths, which led to increased sensitivity and improved image quality. Improvements in workflow and the use of artificial intelligence are among many current trends seen in this field, paving the way for a broad use of MRI. The 125th anniversary of the BJR is a good point to reflect on all these changes and developments and to offer some slightly speculative ideas as to what the future may bring.
Collapse
Affiliation(s)
- Peter Börnert
- Philips Research, Hamburg, Germany.,Department of Radiology, LUMC, Leiden, the Netherlands
| | - David G Norris
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, Netherlands.,Erwin L. Hahn Institute for Magnetic Resonance Imaging, University of Duisburg-Essen, Essen, Germany.,Magnetic Detection and Imaging, Science and Technology Faculty, University of Twente, Enschede, Netherlands
| |
Collapse
|
23
|
Detector clothes for MRI: A wearable array receiver based on liquid metal in elastic tubes. Sci Rep 2020; 10:8844. [PMID: 32483259 PMCID: PMC7264329 DOI: 10.1038/s41598-020-65634-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 05/06/2020] [Indexed: 11/08/2022] Open
Abstract
In modern magnetic resonance imaging, signal detection is performed by dense arrays of radiofrequency resonators. Tight-fitting arrays boost the sensitivity and speed of imaging. However, current devices are rigid and cage-like at the expense of patient comfort. They also constrain posture, limiting the examination of joints. For better ergonomics and versatility, detectors should be flexible, adapt to individual anatomy, and follow posture. Towards this goal, the present work proposes a novel design based on resonators formed by liquid metal in polymer tubes. Textile integration creates lightweight, elastic devices that are worn like pieces of clothing. A liquid-metal array tailored to the human knee is shown to deliver competitive image quality while self-adapting to individual anatomy and adding the ability to image flexion of the joint. Relative to other options for stretchable conductors, liquid metal in elastic tubes stands out by reconciling excellent electrical and mechanical properties with ease of manufacturing.
Collapse
|
24
|
Reber J, Marjanovic J, Brunner DO, Port A, Schmid T, Dietrich BE, Moser U, Barmet C, Pruessmann KP. An In-Bore Receiver for Magnetic Resonance Imaging. IEEE TRANSACTIONS ON MEDICAL IMAGING 2020; 39:997-1007. [PMID: 31484112 DOI: 10.1109/tmi.2019.2939090] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In magnetic resonance imaging, the use of array detection and the number of detector elements have seen a steady increase over the past two decades. As a result, per-channel analog connection via long coaxial cable, as commonly used, poses an increasing challenge in terms of handling, safety, and coupling among cables. This situation is exacerbated when complementary recording of radiofrequency transmission or NMR-based magnetic field sensing further add to channel counts. A generic way of addressing this trend is the transition to digital signal transmission, enabled by digitization and first-level digital processing close to detector coils and sensors in the magnet bore. The foremost challenge that comes with this approach is to achieve high dynamic range, linearity, and phase stability despite interference by strong static, audiofrequency, and radiofrequency fields. The present work reports implementation of a 16-channel in-bore receiver, performing signal digitization and processing with subsequent optical transmission over fiber. Along with descriptions of the system design and construction, performance evaluation is reported. The resulting device is fully MRI compatible providing practically equal performance and signal quality compared to state-of-the-art RF digitizers operating outside the magnet. Its use is demonstrated by examples of head imaging and magnetic field recording.
Collapse
|
25
|
Li GH, Li Y, Zhu GY, Yan TY, Hu XF, Zhang T, Zhang S. Design and verification of 5-channel 1.5T knee joint receiving coil based on wearable technology. Technol Health Care 2019; 28:495-505. [PMID: 31796712 DOI: 10.3233/thc-191817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Over the past 20 years, magnetic resonance receiving coil technology has developed rapidly. The traditional, commercial knee joint coil has a fixed mechanical structure. To meet the imaging needs of most patients, it is necessary to ensure that the mechanical geometry of the coil is as large as possible. Therefore, different quality images can be obtained by filling coefficients under loads of knees of different sizes. Lufkin et al. [1] have demonstrated that the signal-to-noise ratio (SNR) of coil imaging is directly proportional to its filling coefficient, which is S/N≈QL*η. Thus, the pursuit of an optimal coil filling coefficient is an important way to improve the coil imaging quality. OBJECTIVE This study combines wearable concepts and coil development techniques and applies flexible and elastic materials to coil designs. METHODS We used an elastic material instead of the traditional fixed mechanical structure to develop a 1.5T 5-channel knee joint receiving coil that can be attached to knee joints of different sizes within a certain range, allowing the coil to achieve a maximum filling coefficient under the loads of knees of different sizes. RESULTS Compared to commercial 8-channel knee coils, the phantom test and clinical knee joint imaging demonstrated that the SNR of the developed coil increased by four times in the shallow layer and two times in the deep layer, under different load conditions. CONCLUSION This high SNR performance demonstrates potential for the realization of high resolution and fast imaging sequences in knee imaging.
Collapse
Affiliation(s)
- Gui Hao Li
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.,High Field Magnetic Resonance Brain Imaging Laboratory of Sichuan, Chengdu, Sichuan, China.,Key Laboratory for NeuroInformation of Ministry of Education, Chengdu, Sichuan, China.,School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Ye Li
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.,High Field Magnetic Resonance Brain Imaging Laboratory of Sichuan, Chengdu, Sichuan, China.,Key Laboratory for NeuroInformation of Ministry of Education, Chengdu, Sichuan, China
| | - Gai Yan Zhu
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.,High Field Magnetic Resonance Brain Imaging Laboratory of Sichuan, Chengdu, Sichuan, China.,Key Laboratory for NeuroInformation of Ministry of Education, Chengdu, Sichuan, China
| | - Tai Yu Yan
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.,High Field Magnetic Resonance Brain Imaging Laboratory of Sichuan, Chengdu, Sichuan, China.,Key Laboratory for NeuroInformation of Ministry of Education, Chengdu, Sichuan, China
| | - Xia Fei Hu
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.,High Field Magnetic Resonance Brain Imaging Laboratory of Sichuan, Chengdu, Sichuan, China.,Key Laboratory for NeuroInformation of Ministry of Education, Chengdu, Sichuan, China
| | - Tao Zhang
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.,High Field Magnetic Resonance Brain Imaging Laboratory of Sichuan, Chengdu, Sichuan, China.,Key Laboratory for NeuroInformation of Ministry of Education, Chengdu, Sichuan, China
| | - Shuang Zhang
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.,College of Computer Science, Neijiang Normal University, Neijiang, Sichuan, China.,High Field Magnetic Resonance Brain Imaging Laboratory of Sichuan, Chengdu, Sichuan, China.,Key Laboratory for NeuroInformation of Ministry of Education, Chengdu, Sichuan, China.,School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| |
Collapse
|
26
|
Mehmann A, Vogt C, Varga M, Port A, Reber J, Marjanovic J, Pruessmann KP, Sporrer B, Huang Q, Troster G. Automatic Resonance Frequency Retuning of Stretchable Liquid Metal Receive Coil for Magnetic Resonance Imaging. IEEE TRANSACTIONS ON MEDICAL IMAGING 2019; 38:1420-1426. [PMID: 30582533 DOI: 10.1109/tmi.2018.2888959] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Stretchable magnetic resonance (MR) receive coils show shifts in their resonance frequency when stretched. An in-field receiver measures the frequency response of a stretchable coil. The receiver and coil are designed to operate at 128 MHz for a 3T MR scanner. Based on the measured frequency response, we are able to detect the changes of the resonance frequency of the coil. We show a proportional-integral-derivative controller that tracks the changes in resonance frequency and retunes the stretchable coil. The settling time of the control loop is less than 3.8ms. The retuning system reduces the loss in signal-to-noise ratio of phantom images from 1.6 dB to 0.3 dB, when the coil is stretched by 40% and the coil is retuned to 128 MHz.
Collapse
|
27
|
Yeh JNT, Lin JFL. A Flexible and Modular Receiver Coil Array for Magnetic Resonance Imaging. IEEE TRANSACTIONS ON MEDICAL IMAGING 2019; 38:824-833. [PMID: 30295617 DOI: 10.1109/tmi.2018.2873317] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We propose a flexible form-fittingMRI receiver coil array assembledby individualcoilmodules. This design targetsMRI applications requiring a receiver array conforming to the anatomy of various shapes or sizes. Coil modules in our proposed array were arranged with gaps between them. Each coil module had a circumferential shielding structure stacked on top of the coil. Together they achieve robust decoupling when the array was bent differently. Two types of the circumferential shielding structure were investigatedby using full-wave electromagnetic simulations and imaging experiments. Results showed that our flexible coil array had good decoupling between coils whether they were on a flat or curved surface with the S21 magnitude ranged between -18.1 dB and -19.9 dB in simulations, and with the average of off-diagonal entries of the noise correlationmatrix less than 0.047 in experimentalmeasurements. Anatomical images of human brain, calf, and knee were acquired by our seven-channel prototype on a 3T MRI system. The maximal and the average SNR within 50 mm from our array surpassed those from the commercial 32-channel head and 4-channel flexible coil arrays by 2.63/1.35-fold and 3.89/1.50-fold, respectively.
Collapse
|
28
|
Zhang B, Brown R, Cloos M, Lattanzi R, Sodickson D, Wiggins G. Size-adaptable "Trellis" structure for tailored MRI coil arrays. Magn Reson Med 2018; 81:3406-3415. [PMID: 30575119 DOI: 10.1002/mrm.27637] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 10/28/2018] [Accepted: 11/22/2018] [Indexed: 11/12/2022]
Abstract
PURPOSE We present a novel, geometrically adjustable, receive coil array whose diameter can be tailored to the subject in order to maximize sensitivity for a range of body sizes. THEORY AND METHODS A key mechanical feature of the size-adaptable receive array is its trellis structure that was motivated by similar structures found in gardening and fencing. Our implementation is a cylindrical trellis that features encircling, diagonally interleaved slats, which are linked together at intersecting points. The ensemble allows expansion or contraction to be controlled with the angle between the slats. This mechanical frame provides a base for radiofrequency coils wherein approximately constant overlap, and therefore coupling between adjacent elements, is maintained when the trellis is expanded or contracted. We demonstrate 2 trellis coil concepts for imaging lower extremity at 3T: a single-row 8-channel array built on a trellis support structure and a multirow 24-channel array in which the coil elements themselves form the trellis structure. RESULTS We show that the adjustable trellis array can accommodate a range of subject sizes with robust signal-to-noise ratio, loading, and coupling. CONCLUSION The trellis coil concept enables an array of surface coils to expand and contract with negligible effect on tuning, matching, and decoupling. This allows an encircling array to conform closely to anatomy of various sizes, which provides significant gains in signal-to-noise ratio.
Collapse
Affiliation(s)
- Bei Zhang
- Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine, New York, New York.,Center for Advanced Imaging Innovation and Research, New York University School of Medicine, New York, New York
| | - Ryan Brown
- Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine, New York, New York.,Center for Advanced Imaging Innovation and Research, New York University School of Medicine, New York, New York.,Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, New York
| | - Martijn Cloos
- Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine, New York, New York.,Center for Advanced Imaging Innovation and Research, New York University School of Medicine, New York, New York.,Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, New York.,Tech4Health, NYU Langone Health, New York
| | - Riccardo Lattanzi
- Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine, New York, New York.,Center for Advanced Imaging Innovation and Research, New York University School of Medicine, New York, New York.,Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, New York
| | - Daniel Sodickson
- Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine, New York, New York.,Center for Advanced Imaging Innovation and Research, New York University School of Medicine, New York, New York.,Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, New York.,Tech4Health, NYU Langone Health, New York
| | | |
Collapse
|
29
|
Hosseinnezhadian S, Frass-Kriegl R, Goluch-Roat S, Pichler M, Sieg J, Vít M, Poirier-Quinot M, Darrasse L, Moser E, Ginefri JC, Laistler E. A flexible 12-channel transceiver array of transmission line resonators for 7 T MRI. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2018; 296:47-59. [PMID: 30205313 DOI: 10.1016/j.jmr.2018.08.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 08/08/2018] [Accepted: 08/30/2018] [Indexed: 06/08/2023]
Abstract
A flexible transceiver array based on transmission line resonators (TLRs) combining the advantages of coil arrays with the possibility of form-fitting targeting cardiac MRI at 7 T is presented. The design contains 12 elements which are fabricated on a flexible substrate with rigid PCBs attached on the center of each element to place the interface components, i.e. transmit/receive (T/R) switch, power splitter, pre-amplifier and capacitive tuning/matching circuitry. The mutual coupling between elements is cancelled using a decoupling ring-based technique. The performance of the developed array is evaluated by 3D electromagnetic simulations, bench tests, and MR measurements using phantoms. Efficient inter-element decoupling is demonstrated in flat configuration on a box-shaped phantom (Sij < -19 dB), and bent on a human torso phantom (Sij < -16 dB). Acceleration factors up to 3 can be employed in bent configuration with reasonable g-factors (<1.7) in an ROI at the position of the heart. The array enables geometrical conformity to bodies within a large range of size and shape and is compatible with parallel imaging and parallel transmission techniques.
Collapse
Affiliation(s)
- Sajad Hosseinnezhadian
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria; MR Centre of Excellence, Medical University of Vienna, Lazarettgasse 14, 1090 Vienna, Austria; IR4M (Imagerie par Résonance Magnétique Médicale et Multi-Modalités), Bât 220, Univ. Paris-Sud, CNRS, Université Paris-Saclay, 91405 Orsay, France
| | - Roberta Frass-Kriegl
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria; MR Centre of Excellence, Medical University of Vienna, Lazarettgasse 14, 1090 Vienna, Austria
| | - Sigrun Goluch-Roat
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria; MR Centre of Excellence, Medical University of Vienna, Lazarettgasse 14, 1090 Vienna, Austria
| | - Michael Pichler
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria; MR Centre of Excellence, Medical University of Vienna, Lazarettgasse 14, 1090 Vienna, Austria
| | - Jürgen Sieg
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria; MR Centre of Excellence, Medical University of Vienna, Lazarettgasse 14, 1090 Vienna, Austria
| | - Martin Vít
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria; MR Centre of Excellence, Medical University of Vienna, Lazarettgasse 14, 1090 Vienna, Austria; IKEM (Institute for Clinical and Experimental Medicine), Vídeňská 1958/9, 140 21 Praha 4, Czech Republic
| | - Marie Poirier-Quinot
- IR4M (Imagerie par Résonance Magnétique Médicale et Multi-Modalités), Bât 220, Univ. Paris-Sud, CNRS, Université Paris-Saclay, 91405 Orsay, France
| | - Luc Darrasse
- IR4M (Imagerie par Résonance Magnétique Médicale et Multi-Modalités), Bât 220, Univ. Paris-Sud, CNRS, Université Paris-Saclay, 91405 Orsay, France
| | - Ewald Moser
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria; MR Centre of Excellence, Medical University of Vienna, Lazarettgasse 14, 1090 Vienna, Austria
| | - Jean-Christophe Ginefri
- IR4M (Imagerie par Résonance Magnétique Médicale et Multi-Modalités), Bât 220, Univ. Paris-Sud, CNRS, Université Paris-Saclay, 91405 Orsay, France
| | - Elmar Laistler
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria; MR Centre of Excellence, Medical University of Vienna, Lazarettgasse 14, 1090 Vienna, Austria.
| |
Collapse
|
30
|
Frass-Kriegl R, Navarro de Lara LI, Pichler M, Sieg J, Moser E, Windischberger C, Laistler E. Flexible 23-channel coil array for high-resolution magnetic resonance imaging at 3 Tesla. PLoS One 2018; 13:e0206963. [PMID: 30383832 PMCID: PMC6211745 DOI: 10.1371/journal.pone.0206963] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 10/23/2018] [Indexed: 11/18/2022] Open
Abstract
PURPOSE The purpose of this work is the design, implementation and evaluation of a mechanically flexible receive-only coil array for magnetic resonance imaging (MRI) at 3 T that can be applied to various target organs and provides high parallel imaging performance. METHODS A 23-channel array was designed based on a rigid-flex printed circuit board (PCB). The flexible multi-layer part contains the copper traces forming the coil elements. The rigid part of the PCB houses the solder joints and lumped elements. The coil housing consists of rigid caps mounted above the rigid parts. Adhesive PTFE sheets cover all flexible parts. The developed array was tested on the bench as well as in phantom and in vivo MRI experiments employing parallel imaging acceleration factors up to six. RESULTS Efficient mutual decoupling between receive elements and detuning between receive array and body coil was achieved. An increased signal-to-noise ratio in comparison to commercial reference coils is demonstrated, especially in regions close to the developed array and for high parallel imaging acceleration factors. Exemplary in vivo images of head, ankle, knee, shoulder and hand are presented. CONCLUSION Based on high sensitivity close to the array and low g-factors, this flexible coil is well suited for studies of occipital and temporal cortex, as well as musculoskeletal targets like knee, ankle, elbow and wrist.
Collapse
Affiliation(s)
- Roberta Frass-Kriegl
- Division MR Physics, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Lucia Isabel Navarro de Lara
- Division MR Physics, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Michael Pichler
- Division MR Physics, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Jürgen Sieg
- Division MR Physics, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Ewald Moser
- Division MR Physics, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Christian Windischberger
- Division MR Physics, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Elmar Laistler
- Division MR Physics, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| |
Collapse
|
31
|
Mehmann A, Varga M, Vogt C, Port A, Reber J, Marjanovic J, Pruessmann KP, Troster G. On the Bending and Stretching of Liquid Metal Receive Coils for Magnetic Resonance Imaging. IEEE Trans Biomed Eng 2018; 66:1542-1548. [PMID: 30307855 DOI: 10.1109/tbme.2018.2875436] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The eGaIn coil on neoprene demonstrated in this paper presents a stretchable radio frequency receive coil for magnetic resonance imaging (MRI). The coil with dimensions [Formula: see text] is tuned to resonate at 128 MHz for 3 T MRI. We investigate the effect of stretching (up to 40% strain) and bending (50 mm radius of curvature) of the coil on the coil's resistance and resonance frequency. Measurements and simulations show a decrease in resonance frequency of 2.5 MHz per 10% strain. The higher resistivity of liquid metal compared to copper reduces the SNR of MRI scans by 34%; therefore, a tradeoff between flexibility and performance remains. Nevertheless, we have successfully performed MRI scans with the liquid metal coil.
Collapse
|
32
|
Lopez Rios N, Foias A, Lodygensky G, Dehaes M, Cohen-Adad J. Size-adaptable 13-channel receive array for brain MRI in human neonates at 3 T. NMR IN BIOMEDICINE 2018; 31:e3944. [PMID: 29928791 DOI: 10.1002/nbm.3944] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 03/30/2018] [Accepted: 04/24/2018] [Indexed: 06/08/2023]
Abstract
Neonatal brain injury suffered by preterm infants and newborns with some medical conditions can cause significant neurodevelopmental disabilities. MRI is a preferred method to detect these accidents and perform in vivo evaluation of the brain. However, the commercial availability and optimality of receive coils for the neonatal brain is limited, which in many cases leads to images lacking in quality. As extensively demonstrated, receive arrays closely positioned around the scanned part provide images with high signal-to-noise ratios (SNRs). The present work proposes a pneumatic-based MRI receive array that can physically adapt to infant head dimensions from 27-week premature to 1.5 months old. Average SNR increases of up to 68% in the head region and 122% in the cortex region, compared with a 32-channel commercial head coil, were achieved at 3 T. The consistent SNR distribution obtained through the complete coil size range, specifically in the cortex, allows the acquisition of images with similar quality across a range of head dimensions, which is not possible with fixed-size coils due to the variable coil-to-head distance. The risks associated with mechanical pressure on the neonatal head are minimal and the head motion is restricted. The method could be used in coil designs for other age groups, body parts and subjects.
Collapse
Affiliation(s)
- Nibardo Lopez Rios
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, QC, Canada
- Sainte-Justine Hospital University Center, Montreal, QC, Canada
- Centro de Biofisica Medica, Universidad de Oriente, Santiago de Cuba, Cuba
| | - Alexandru Foias
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, QC, Canada
| | - Gregory Lodygensky
- Sainte-Justine Hospital University Center, Montreal, QC, Canada
- Department of Pediatrics, Faculty of Medicine, University of Montreal, Montreal, QC, Canada
- Montreal Heart Institute, Montreal, QC, Canada
| | - Mathieu Dehaes
- Sainte-Justine Hospital University Center, Montreal, QC, Canada
- Department of Radiology, Radio-oncology and Nuclear Medicine, University of Montreal, Montreal, QC, Canada
- Institute of Biomedical Engineering, University of Montreal, Montreal, QC, Canada
| | - Julien Cohen-Adad
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, QC, Canada
- Functional Neuroimaging Unit, CRIUGM, University of Montreal, Montreal, QC, Canada
| |
Collapse
|
33
|
Affiliation(s)
- Elmar Laistler
- Centre for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.,MR Centre of Excellence, Medical University of Vienna, Vienna, Austria
| | - Ewald Moser
- Centre for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria. .,MR Centre of Excellence, Medical University of Vienna, Vienna, Austria.
| |
Collapse
|
34
|
Gruber B, Froeling M, Leiner T, Klomp DW. RF coils: A practical guide for nonphysicists. J Magn Reson Imaging 2018; 48:590-604. [PMID: 29897651 PMCID: PMC6175221 DOI: 10.1002/jmri.26187] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 04/23/2018] [Indexed: 11/09/2022] Open
Abstract
Radiofrequency (RF) coils are an essential MRI hardware component. They directly impact the spatial and temporal resolution, sensitivity, and uniformity in MRI. Advances in RF hardware have resulted in a variety of designs optimized for specific clinical applications. RF coils are the "antennas" of the MRI system and have two functions: first, to excite the magnetization by broadcasting the RF power (Tx-Coil) and second to receive the signal from the excited spins (Rx-Coil). Transmit RF Coils emit magnetic field pulses ( B1+) to rotate the net magnetization away from its alignment with the main magnetic field (B0 ), resulting in a transverse precessing magnetization. Due to the precession around the static main magnetic field, the magnetic flux in the receive RF Coil ( B1-) changes, which generates a current I. This signal is "picked-up" by an antenna and preamplified, usually mixed down to a lower frequency, digitized, and processed by a computer to finally reconstruct an image or a spectrum. Transmit and receive functionality can be combined in one RF Coil (Tx/Rx Coils). This review looks at the fundamental principles of an MRI RF coil from the perspective of clinicians and MR technicians and summarizes the current advances and developments in technology. LEVEL OF EVIDENCE 1 Technical Efficacy: Stage 6.
Collapse
Affiliation(s)
- Bernhard Gruber
- A.A. Martinos Center for Biomedical Imaging, Harvard‐MIT Division of Health Sciences & Technology, Massachusetts General HospitalCharlestownMassachusettsUSA
- Department of Radiology, Harvard Medical SchoolMassachusetts General HospitalBostonMassachusettsUSA
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaViennaAustria
| | - Martijn Froeling
- Department of RadiologyUniversity Medical Center UtrechtUtrechtThe Netherlands
| | - Tim Leiner
- Department of RadiologyUniversity Medical Center UtrechtUtrechtThe Netherlands
| | - Dennis W.J. Klomp
- Department of RadiologyUniversity Medical Center UtrechtUtrechtThe Netherlands
| |
Collapse
|
35
|
Varga M, Mehmann A, Marjanovic J, Reber J, Vogt C, Pruessmann KP, Tröster G. Adsorbed Eutectic GaIn Structures on a Neoprene Foam for Stretchable MRI Coils. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1703744. [PMID: 29027724 DOI: 10.1002/adma.201703744] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 08/25/2017] [Indexed: 06/07/2023]
Abstract
Stretchable conductors based on eutectic gallium-indium (eGaIn) alloy are patterned on a polychloroprene substrate (neoprene foam) using stencil printing. By tuning the amount of eGaIn on the neoprene substrate, different strain-sensitivity of electrical resistance is achieved. Conductors with a layer of eGaIn, which adsorbs to the walls of 60-100 µm wide neoprene cells, change their electrical resistance for 5% at 100% strain. When the amount of eGaIn is increased, the cells are filled with eGaIn and the strain-sensitivity of the electrical resistance rises to 300% at 100% strain. The developed conductors are patterned as stretchable on-body coils for receiving magnetic signals in a clinical magnetic resonance imaging setup. First images with a stretchable coil are acquired on an orange and compared to the images that are recorded using a rigid copper coil of the same size.
Collapse
Affiliation(s)
- Matija Varga
- Electronics Laboratory, ETH Zurich, Gloriastrasse 35, 8092, Zurich, Switzerland
| | - Andreas Mehmann
- Electronics Laboratory, ETH Zurich, Gloriastrasse 35, 8092, Zurich, Switzerland
| | - Josip Marjanovic
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Gloriastrasse 35, 8092, Zurich, Switzerland
| | - Jonas Reber
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Gloriastrasse 35, 8092, Zurich, Switzerland
| | - Christian Vogt
- Electronics Laboratory, ETH Zurich, Gloriastrasse 35, 8092, Zurich, Switzerland
| | - Klaas Paul Pruessmann
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Gloriastrasse 35, 8092, Zurich, Switzerland
| | - Gerhard Tröster
- Electronics Laboratory, ETH Zurich, Gloriastrasse 35, 8092, Zurich, Switzerland
| |
Collapse
|
36
|
Byron K, Robb F, Stang P, Vasanawala S, Pauly J, Scott G. An RF-gated wireless power transfer system for wireless MRI receive arrays. CONCEPTS IN MAGNETIC RESONANCE. PART B, MAGNETIC RESONANCE ENGINEERING 2017; 47B:e21360. [PMID: 31057343 PMCID: PMC6498852 DOI: 10.1002/cmr.b.21360] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In MRI systems, cable-free receive arrays would simplify setup while reducing the bulk and weight of coil arrays and improve patient comfort and throughput. Since battery power would limit scan time, wireless power transfer (WPT) is a viable option to continuously supply several watts of power to on-coil electronics. To minimize added noise and decouple the wireless power system from MRI coils, restrictions are placed on the coil geometry of the wireless power system, which are shown to limit its efficiency. Continuous power harvesting can also cause a large increase in the background noise of the image due to diode rectifier up-conversion of noise around the frequency of the transmitted power. However, by RF gating the transmitted power off during the MRI receive time while continuing to supply power from a storage capacitor, WPT is demonstrated to have minimal impact on image quality at received power levels up to 11 W. The integration of WPT with a 1.5T scanner is demonstrated.
Collapse
Affiliation(s)
- Kelly Byron
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | | | | | | | - John Pauly
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Greig Scott
- Department of Electrical Engineering, Stanford University, Stanford, CA USA
| |
Collapse
|
37
|
An open 8-channel parallel transmission coil for static and dynamic 7T MRI of the knee and ankle joints at multiple postures. Magn Reson Med 2017. [DOI: 10.1002/mrm.26804] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
|
38
|
Corea JR, Lechene PB, Lustig M, Arias AC. Materials and methods for higher performance screen-printed flexible MRI receive coils. Magn Reson Med 2016; 78:775-783. [PMID: 27612330 DOI: 10.1002/mrm.26399] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 07/19/2016] [Accepted: 08/09/2016] [Indexed: 11/10/2022]
Abstract
PURPOSE To develop methods for characterizing materials used in screen-printed MRI coils and improve signal-to-noise ratio (SNR) with new lower-loss materials. METHODS An experimental apparatus was created to characterize dielectric properties of plastic substrates used in receive coils. Coils were fabricated by screen printing conductive ink onto several plastic substrates. Unloaded and sample loaded quality factor (QUnloaded /QLoaded ) measurements and scans on a 3T scanner were used to characterize coil performance. An experimental method was developed to describe the relationship between a coil's QUnloaded and the SNR it provides in images of a phantom. In addition, 3T scans of a phantom and the head of a volunteer were obtained with a proof-of-concept printed eight-channel array, and the results were compared with a commercial 12-channel array. RESULTS Printed coils with optimized substrates exhibited up to 97% of the image SNR when compared with a traditional coil on a loading phantom. QUnloaded and the SNR of coils were successfully correlated. The printed array resulted in images comparable to the quality given by the commercial array. CONCLUSION Using the proposed methods and materials, the SNR of printed coils approached that of commercial coils while using a new fabrication technique that provided more flexibility and close contact with the patient's body. Magn Reson Med 78:775-783, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
Collapse
Affiliation(s)
- Joseph R Corea
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, California, USA
| | - P Balthazar Lechene
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, California, USA
| | - Michael Lustig
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, California, USA
| | - Ana C Arias
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, California, USA
| |
Collapse
|
39
|
Mazzoli V, Nederveen AJ, Oudeman J, Sprengers A, Nicolay K, Strijkers GJ, Verdonschot N. Water and fat separation in real-time MRI of joint movement with phase-sensitive bSSFP. Magn Reson Med 2016; 78:58-68. [DOI: 10.1002/mrm.26341] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Revised: 06/20/2016] [Accepted: 06/20/2016] [Indexed: 01/04/2023]
Affiliation(s)
- Valentina Mazzoli
- Biomedical NMR, Department of Biomedical Engineering; Eindhoven University of Technology; Eindhoven The Netherlands
- Department of Radiology; Academic Medical Center; Amsterdam The Netherlands
- Orthopaedic Research Lab; Radboud University Medical Center; Nijmegen The Netherlands
| | - Aart J. Nederveen
- Department of Radiology; Academic Medical Center; Amsterdam The Netherlands
| | - Jos Oudeman
- Department of Radiology; Academic Medical Center; Amsterdam The Netherlands
| | - Andre Sprengers
- Orthopaedic Research Lab; Radboud University Medical Center; Nijmegen The Netherlands
- Laboratory of Biomechanical Engineering; University of Twente; Enschede The Netherlands
| | - Klaas Nicolay
- Biomedical NMR, Department of Biomedical Engineering; Eindhoven University of Technology; Eindhoven The Netherlands
| | - Gustav J. Strijkers
- Biomedical NMR, Department of Biomedical Engineering; Eindhoven University of Technology; Eindhoven The Netherlands
- Biomedical Engineering and Physics; Academic Medical Center; Amsterdam The Netherlands
| | - Nico Verdonschot
- Orthopaedic Research Lab; Radboud University Medical Center; Nijmegen The Netherlands
- Laboratory of Biomechanical Engineering; University of Twente; Enschede The Netherlands
| |
Collapse
|
40
|
A target field design of open multi-purpose RF coil for musculoskeletal MR imaging at 3T. Magn Reson Imaging 2016; 34:1064-70. [PMID: 27114344 DOI: 10.1016/j.mri.2016.04.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 04/06/2016] [Accepted: 04/17/2016] [Indexed: 11/22/2022]
Abstract
Musculoskeletal MR imaging under multi-angle situations plays an increasingly important role in assessing joint and muscle tissues system. However, there are still limitations due to the closed structures of most conventional RF coils. In this study, a time-harmonic target-field method was employed to design open multi-purpose coil (OMC) for multi-angle musculoskeletal MR imaging. The phantom imaging results suggested that the proposed OMC could achieve homogeneously distributed magnetic field and high signal-to-noise ratio (SNR) of 239.04±0.83 in the region of interest (ROI). The maximum temperature in the heating hazard test was 16°C lower than the standard regulation, which indicated the security of the designed OMC. Furthermore, to demonstrate the effectiveness of the proposed OMC for musculoskeletal MR imaging, especially for multi-angle imaging, a healthy volunteer was examined for MR imaging of elbow, ankle and knee using OMC. The in vivo imaging results showed that the proposed OMC is effective for MR imaging of musculoskeletal tissues at different body parts, with satisfied B1 field homogeneity and SNR. Moreover, the open structure of the OMC could provide a large joint movement region. The proposed open multi-purpose coil is feasible for musculoskeletal MR imaging, and potentially, it is more suitable for the evaluation of musculoskeletal tissues under multi-angle conditions.
Collapse
|
41
|
Corea JR, Flynn AM, Lechêne B, Scott G, Reed GD, Shin PJ, Lustig M, Arias AC. Screen-printed flexible MRI receive coils. Nat Commun 2016; 7:10839. [PMID: 26961073 PMCID: PMC5553354 DOI: 10.1038/ncomms10839] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Accepted: 01/27/2016] [Indexed: 02/06/2023] Open
Abstract
Magnetic resonance imaging is an inherently signal-to-noise-starved technique that limits the spatial resolution, diagnostic image quality and results in typically long acquisition times that are prone to motion artefacts. This limitation is exacerbated when receive coils have poor fit due to lack of flexibility or need for padding for patient comfort. Here, we report a new approach that uses printing for fabricating receive coils. Our approach enables highly flexible, extremely lightweight conforming devices. We show that these devices exhibit similar to higher signal-to-noise ratio than conventional ones, in clinical scenarios when coils could be displaced more than 18 mm away from the body. In addition, we provide detailed material properties and components performance analysis. Prototype arrays are incorporated within infant blankets for in vivo studies. This work presents the first fully functional, printed coils for 1.5- and 3-T clinical scanners. Signal-to-noise ratio is one of the key factors that currently limit the diagnostic image quality and patient conditions of magnetic resonance imaging. Here, Corea et al. use fully printed flexible receive coils, conforming to patient bodies, to improve signals and patient comfort in clinical scanners.
Collapse
Affiliation(s)
- Joseph R Corea
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, USA
| | - Anita M Flynn
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, USA
| | - Balthazar Lechêne
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, USA
| | - Greig Scott
- Department of Electrical Engineering, Stanford University, Stanford, California 94305, USA
| | - Galen D Reed
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, USA.,Department of Bioengineering, University of California, San Francisco, California 94722, USA
| | - Peter J Shin
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, USA.,Department of Bioengineering, University of California, San Francisco, California 94722, USA
| | - Michael Lustig
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, USA
| | - Ana C Arias
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, USA
| |
Collapse
|
42
|
Nordmeyer-Massner JA, Pruessmann KP, Wyss M, Manoliu A, Hodler J, Andreisek G, Mamisch-Saupe N. MR imaging of healthy knees in varying degrees of flexion using a stretchable coil array provides comparable image quality compared to a standard knee coil array. Eur J Radiol 2016; 85:518-23. [PMID: 26860662 DOI: 10.1016/j.ejrad.2015.12.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 08/23/2015] [Accepted: 12/09/2015] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Stretchable coils allow knee imaging at varying degrees of flexion. Purpose was to compare a new-developed stretchable 8-channel to a standard 8-channel knee coil array by means of quantitative and qualitative image analysis. MATERIAL AND METHODS IRB approved prospective study. Knee MR imaging in 10 healthy volunteers was performed at 3T using a standard 8-channel and a new-developed stretchable 8-channel coil array at 0°, 45°, and 60° of flexion and at 0° (standard coil). Image parameters were identical. Signal-to-noise ratio (SNR) was determined by combining the images with separately acquired noise data on a pixel-by-pixel basis using MATLAB routines (Natick, MA, USA). Images were qualitatively analysed by two independent radiologists who graded the visibility of several anatomic structures from 1=not visible to 5=excellent. ANOVA, Wilcoxon and kappa statistics were used. RESULTS Mean SNR±standarddeviation of bone was 54.7±10.4 and of muscle 28.0± 4.4 using the stretchable coil array and 54.6±8.2 and 33.4±4.5, respectively, using the standard knee coil array. No statistically significant SNR differences were found between both arrays (bone, p=0.960; muscle, p=0.132). SNR was not degraded at higher degrees of flexion. The qualitative image analysis did not reveal statistically significant differences between the stretchable and standard coil array with regard to the visibility of anatomic structures (p=0.026-1.000). Overall kappa was 0.714. CONCLUSION Stretchable 8-channel coil arrays provide similar SNR and visibility of anatomic structures compared to standard 8-channel knee coil arrays. MR imaging with high SNR will now be possible in flexed knees.
Collapse
Affiliation(s)
| | - Klaas P Pruessmann
- Institute for Biomedical Engineering, University and ETH Zurich, Switzerland
| | - Michael Wyss
- Institute for Biomedical Engineering, University and ETH Zurich, Switzerland
| | - Andrei Manoliu
- Institute for Biomedical Engineering, University and ETH Zurich, Switzerland; Institute for Diagnostic and Interventional Radiology, Department of Radiology, University Hospital Zurich, Switzerland.
| | - Jürg Hodler
- Institute for Diagnostic and Interventional Radiology, Department of Radiology, University Hospital Zurich, Switzerland
| | - Gustav Andreisek
- Institute for Diagnostic and Interventional Radiology, Department of Radiology, University Hospital Zurich, Switzerland
| | - Nadja Mamisch-Saupe
- Institute for Diagnostic and Interventional Radiology, Department of Radiology, University Hospital Zurich, Switzerland
| |
Collapse
|
43
|
Lange T, Maclaren J, Herbst M, Lovell-Smith C, Izadpanah K, Zaitsev M. Knee cartilage MRI with in situ mechanical loading using prospective motion correction. Magn Reson Med 2016; 71:516-23. [PMID: 23440894 DOI: 10.1002/mrm.24679] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
PURPOSE To assess the feasibility of high resolution knee cartilage MRI with in situ mechanical loading using optical tracking to compensate for motion. METHODS In vivo cartilage MRI with in situ mechanical loading is demonstrated on a clinical 3T system for the patellofemoral as well as for the tibiofemoral knee joint using a T1-weighted spoiled three-dimensional gradient-echo sequence. Prospective motion correction is performed with a moiré phase tracking system consisting of an in-bore camera and a single tracking marker attached to the skin. RESULTS Rigid-body approximation required for prospective correction with optical motion tracking is fulfilled well enough for the patellofemoral as well as for the tibiofemoral joint when the tracking marker is attached to the knee cap and the shin, respectively. Presaturation proves to be efficient in suppressing pulsation artifacts from the popliteal artery and residual motion artifacts primarily arising from nonrigid motion of the posterior knee compartment. CONCLUSION The proposed technique enables knee cartilage imaging under in situ mechanical loading with submillimeter spatial resolution devoid of significant motion artifacts and thus appropriate for cartilage volumetry. It has the potential to provide new insight into the biomechanics of the knee and might complement the panoply of diagnostic MR methods for osteoarthritis.
Collapse
Affiliation(s)
- Thomas Lange
- Department of Radiology, Medical Physics, University Medical Center Freiburg, Freiburg, Germany
| | | | | | | | | | | |
Collapse
|
44
|
Jia F, Yuan H, Zhou D, Zhang J, Wang X, Fang J. Knee MRI under varying flexion angles utilizing a flexible flat cable antenna. NMR IN BIOMEDICINE 2015; 28:460-467. [PMID: 25740180 DOI: 10.1002/nbm.3264] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2014] [Revised: 12/04/2014] [Accepted: 12/30/2014] [Indexed: 06/04/2023]
Abstract
The aim of this study is to fabricate and test a novel flexible flat cable antenna (FFCA) for MRI of the knee at different flexion angles. The FFCA was made of a flat cable, a tuning/matching circuit and a signal transmission line. To test its feasibility and validity, in vitro and in vivo experiments were carried out on a 3.0 T MR scanner. The in vitro experiment suggested that the proposed FFCA could achieve a high signal-to-noise ratio (SNR) of 336, while the SNR of an eight-channel knee coil was 291, and phantom images from the FFCA are homogeneously distributed. In the in vivo experiment, the FFCA had a higher SNR of 169 in the region of interest and more than 48.5 cm of longitudinal coverage, while the corresponding values for the commercial coil were 153 and 22.5 cm. Finally, five sagittal knee images at different flexion angles were acquired. The FFCA could acquire satisfactory knee images at different flexion angles, with the advantages of simplicity, low cost, large field of view and high SNR. It may therefore be further used to improve MR image quality of the knee joint.
Collapse
Affiliation(s)
- Fan Jia
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | | | | | | | | | | |
Collapse
|
45
|
d'Entremont AG, Nordmeyer-Massner JA, Bos C, Wilson DR, Pruessmann KP. Do dynamic-based MR knee kinematics methods produce the same results as static methods? Magn Reson Med 2012; 69:1634-44. [DOI: 10.1002/mrm.24425] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Revised: 06/14/2012] [Accepted: 06/27/2012] [Indexed: 12/24/2022]
|